Power operated knife safety switch



Dec. 12, 1967 J. M. HANSEN 3,358,108

POWER OPE-RATED KNIFE SAFETY SWITCH Filed Feb. 10, 1966 INVENTOR. JOHNM. HANSEN MAaf Z 723 ATTORNEY United States Patent Connecticut FiledFeb. 10, 1966, Ser. No. 526,541 6 Claims. (Cl. 200-157) This inventionrel-ates to a safety switch for power operated knives and other toolswhich cannot be actuated accidentally oruninten-tionally to close switchcontacts and thereby produce reciprocatory movement of the knife bladesor undesired movement of tool parts.

The main object of the invention is to provide a switch closing devicewith means for automatically locking a switch actuating member innondepressible position, whereby accidental bumping or pushing of theswitch button cannot result in depression of the button and closing ofthe switch contacts. Another object is to provide a switch actuatingmember which remains in locked position until released by manualpressure applied against a trigger portion of said actuating member,followed by manual depression of the switch actuating button whilepressure on the trigger is maintained by the user of the knife or othertool.

The trigger part of the switch actuating member is located on theunderside of the hand grip portion of the knife handle or tool forconvenient manipulation by the forefinger while the thumb is used todepress the switch button located on the upper surface of the hand gripportion. The requirement for initial manipulation of the trigger,followed by sustained simultaneous pressure in opposite directions onthe trigger and button, prevents unintentional closing of the switchcontacts.

In the drawings:

FIG. 1 is an elevational side view, partly in section, of the forwardportion of a power operated knife embodying my safety switch, showingthe switch actuating member in locked position.

FIG. 2 is an elevational side view, partly in section, showing theswitch actuating member in unlocked position, as it appears after thetrigger has been raised by applying pressure thereon.

FIG. 3 is a view similar to FIG. 2, showing the switch actuating memberin unlocked position and the switch button depressed, as they appearwhen simultaneous pressure has been applied in opposite directions onsaid trigger and button to thereby close the switch contacts.

FIG. 4 is a top plan view of the switch actuating member.

In that embodiment of the invention shown in the drawings, indicates aknife handle housing, as a whole, provided with hand grip portion 11,knife blades 12, and blade guards '13. The housing 10 has formed thereinor attached thereto a horizontal platform 14 spaced from the top wall15, and a curved wall 16 provided with an opening 17 below the hand gripportion 11. A switch button opening 18 is located in the top wall 15.

The safety switch of my invention comprises an actuating member 20provided on its top with a switch button 21, a forward end 22 located inthe space between the platform 14 and top wall 15, a rearwardlyextending lever 23 having its trigger end 24 exposed through the opening17, and a depending foot or contact member 25. The member 25 has formedon its forward face a shoulder 26 which is complemental to, and bearsupon, the shoulder surface 27 on the end of the platform 14, when thetrigger 24 bears on the lower edge 28 which defines the opening 17 inthe housing.

A leaf spring 30, generally U-shaped in form, has part of its fiat bodyresting on the platform 14, with the spring end 31 abutting the stop 32on the platform. The

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upper part 33 of the spring extends toward the member 20 and has a smallhole therein for engagement by a depending projection 34 on the forwardend 22 of said member 20.

In the embodiment of the invention shown in the drawings, the dependingcontact member 25 is shown as having a contact 35 directly locatedthereon, for making contact with a fixed contact 36 connected toconductors 37. However, it is to be understood that the switch contactsmay be separate from the actuating member 20, and that the dependingmember 25 may actuate a movable contact (not shown) in place of having acontact directly mounted thereon.

When the knife is not in use, the actuating member 20 is in the positionshown in FIG. 1, with the spring 30 urging the foiward end 22 upwardly,and theexposed trigger 24 bearing on the edge 28 of the housing wall 16.In this position, the shoulder 26 on the actuating member engages theshoulder 27 on the platform 14. The switch button 21 cannot be depressedbecause of the stops provided by the parts 26-27 and 24-28. Thereforeaccidental or unintentional pressure applied to the button 21 has noeifect.

In order to actuate the switch, the user must apply pressure against theexposed trigger 24 as shown in FIG. 2, thereby raising the trigger leverand moving the shoulder 26 in a pivotal movement out of engagement withthe shoulder 27. While maintaining the pressure on the trigger, the userdepresses the button 21 as shown in FIG. 3, thereby moving the contactmember 25 into switch closing position.

The surface of the shoulder 26 serves as a movable fulcrum for thetrigger lever 23 when pressure is applied to the exposed end 24 to movethe switch actuating member pivotally as a whole out of locked positionso that the button 21 can be depressed and the contact member 25 movedinto the position shown in FIG. 3.

As soon as pressure is withdrawn from the button and trigger, the partsare automatically restored to the position shown in FIG. 1, where theswitch actuating member is again locked and actuation of the switchbutton 21 prevented.

Changes may be made in details of construction and arrangement of partswithout departing from the scope of the inventionas defined by theappended claims.

I claim:

1. In a power operated tool provided with a housing having two spacedapart openings therein, a safety switch in the housing comprising (a) amanually operable switch actuating member including a trigger accessiblethrough one of said openings in the housing and a button accessiblethrough the other opening,

(b) a contact member on the actuating member,

(c) a fixed support in the housing,

(d) a bearing surface extending transversely of the actuating member forbearing on the fixed support and preventing depression of the button,and

(e) yielding means bearing on the fixed support and urging the actuatingmember into support-engaging position,

(f) said actuating member being pivotally movable about said bearingsurface as a non-fixed fulcrum when the trigger is depressed relativelyto the housing, whereby the actuating member is moved out ofsupport-engaging position and depression of the button is permittedwhile said trigger is depressed.

2. The safety switch defined by claim 1, in which the transverselyextending bearing surface is a shoulder on the contact member portion ofthe actuating member and complemental to the fixed support.

3. .In a power operated knife provided with a housing having a. handgrip portion spaced from the housing and spaced apart openings in thehousing and hand grip portion, a safety switch in the housing comprising(a) a manually operable switch actuating member including a triggeraccessible through the opening in the hand grip portion, and a buttonaccessible through the opening in the housing,

(b) a contact member depending from the actuating member, a fixedsupport in the housing spaced from the housing wall, I

(d) a bearing surface extending transversely of the actuating member forbearing on the vfixed support and preventing depression of the button,and

(e) yielding means bearing on the fixed support and urging the actuatingmember into support-engaging position,

(f) said actuating member being pivotally movable about said bearingsurface as a non-fixed fulcrum when the trigger is depressed relativelyto the hand grip portion of the housing, whereby the actuating member ismoved out of support-engaging position and depression of the button ispermitted while said trigger is depressed.

4. The safety switch defined by claim 3, in which the contact memberdepends from the actuating member beneath said button, and the yieldingmeans bears on the fixed support and on the forward end of the actuatingmember to urge the actuating member into supportengaging position.

5. The safety switch defined by claim 3, in which the actuating memberhas a projection on its forward end, and the yielding means is a flatspring bent into U-form with one of its arms bearing on the fixedsupportand the other of its arms .having a hole therein which is engaged by theprojection on the actuating member.

6. The safety switch defined by claim 3, in which the transverselyextending bearing surface is a shoulderon the contact member portion ofthe actuating member and complemental to the fixed support.

References Cited UNITED STATES PATENTS 2,390,846 12/1945 Obszarny200-157 FOREIGN PATENTS 619,571 4/1961 Italy. 649,986 12/1962 Italy.

ROBERT K. SCI-IAEFER, Primary Examiner.

H. BURKE, Assistant Examiner.

1. IN A POWER OPERATED TOOL PROVIDED WITH A HOUSING HAVING TWO SPACEDAPART OPENINGS THEREIN, A SAFETY SWITCH IN THE HOUSING COMPRISING (A) AMANUALLY OPERABLE SWITCH ACTUATING MEMBER INCLUDING A TRIGGER ACCESSIBLETHROUGH ONE OF SAID OPENINGS IN THE HOUSING AND A BUTTON ACCESSIBLETHROUGH THE OTHER OPENING, (B) A CONTACT MEMBER ON THE ACTUATING MEMBER,(C) A FIXED SUPPORT IN THE HOUSING, (D) A BEARING SURFACE EXTENDINGTRANSVERSELY OF THE ACTUATING MEMBER FOR BEARING ON THE FIXED SUPPORTAND PREVENTING DEPRESSION OF THE BUTTON, AND (E) YIELDING MEANS BEARINGON THE FIXED SUPPORT-ENGAGING URGING THE ACTUATING MEMBER INTOSUPPORT-ENGAGING POSITION, (F) SAID ACTUATING MEMBER BEING PIVOTALLYMOVABLE ABOUT SAID BEARING SURFACE AS A NON-FIXED FULCRUM WHEN THETRIGGER IS DEPRESSED RELATIVELY TO THE HOUSING, WHEREBY THE ACTUATINGMEMBER IS MOVED OUT OF SUPPORT-ENGAGING POSITION AND DEPRESSION OF THEBUTTON IS PERMITTED WHILE SAID TRIGGER IS DEPRESSED.